Embodiments of the present disclosure relate generally to the field of drilling and processing of wells. More particularly, present embodiments relate to a system and method for addressing stick-slip issues during certain drilling operations.
In conventional oil and gas operations, a well is typically drilled to a desired depth with a drill string, which may include drill pipe and a drill bit. The drill pipe may include multiple sections of tubular that are coupled to one another by threaded connections or tool joints. During a drilling process, the drill string may be supported and hoisted about a drilling rig and be lowered into a well. A drive system (e.g., a top drive) at the surface may rotate the drill string to facilitate drilling a borehole. Because the drill string is a slender structure relative to the length of the borehole, the drill string is subject to various vibrations or oscillations due to the interaction with the borehole wall.
Stick-slip may be generally defined as the torsional vibration of downhole components or equipment (e.g., drill pipe, drill bit), as it slides against the edges of the borehole. Stick-slip oscillations are severe, self-sustained and periodic torque fluctuations of the drill string torque. The oscillations are driven by nonlinear downhole friction and characterized by large bit speed variations, sometimes up to three times of its nominal value. The reflection of these downhole oscillations can be sensed on the surface through fluctuation of the surface torque, when the surface drive system (e.g., the top drive) is running in a speed control mode. Running with a constant speed, the surface drive system may act as an effective reflector. As a result, vibrational energy is going back and forth along the drill string, and severe torsional oscillations may build up. Stick-slip oscillations are recognized as being a major source of problems such as fatigue failures, excessive bit wear, and poor drilling rate.